Single-structure wireless charging receiver systems having multiple receiver coils

Abstract

Embodiments disclosed herein describe a wireless power receiving system for an electronic device includes: a first inductor coil configured to receive power primarily at a first frequency and from magnetic fields propagating in a first direction; and a second inductor coil configured to receive power primarily at a second frequency and from magnetic fields propagating in a second direction, wherein the first frequency is different than the second frequency.

What is claimed is: 
     
       1. A wireless charging receiver system, comprising:
 a primary coil formed of a plurality of turns of stranded wire wound about a primary axis and configured to receive wireless power from time-varying magnetic fields generated at a first frequency and in a first direction; 
 a ferromagnetic shield disposed over at least two adjacent surfaces of the primary coil and over a portion of entire circumference of the at least two adjacent surfaces such that an annular segment of the primary coil is uncovered by the ferromagnetic shield; and 
 a secondary coil formed of a plurality of turns of stranded wire wound about a secondary axis disposed along a circumference centered around the primary axis, the secondary coil covers overlapping portions of the ferromagnetic shield and the primary coil and is configured to receive wireless power from time-varying magnetic fields generated at a second frequency different from the first frequency and in a second direction different from the first direction. 
 
     
     
       2. The wireless charging receiver system of  claim 1 ; wherein the ferromagnetic shield extends from a first radial location to a second radial location different from the first radial location. 
     
     
       3. The wireless charging receiver system of  claim 2 , wherein the secondary coil extends from a third radial location to a fourth radial location different from the third radial location. 
     
     
       4. The wireless charging receiver system of  claim 1 , wherein the at least two adjacent surfaces of the primary coil comprise an inner surface of the primary coil and a top surface of the primary coil. 
     
     
       5. The wireless charging receiver system of  claim 1 , wherein the secondary coil and the annular segment of the primary coil that is uncovered by the ferromagnetic shield are positioned in opposite halves of the wireless charging receiver system. 
     
     
       6. The wireless charging receiver system of  claim 1 , wherein the primary coil has a circular profile. 
     
     
       7. The wireless charging receiver system of  claim 6 , wherein the ferromagnetic shield comprises an inner edge and an outer edge, the inner edge includes two flat edges disposed in opposite halves of the ferromagnetic shield, and the outer edge has the circular profile. 
     
     
       8. The wireless charging receiver system of  claim 1 ; wherein the primary coil has an oblong profile comprising a first straight segment, a second straight segment, and two curved segments positioned between the first and second straight segments. 
     
     
       9. The wireless charging receiver system of  claim 8 , wherein the ferromagnetic shield comprises an inner edge and an outer edge, both of which include two flat edges disposed in opposite left and right halves of the ferromagnetic shield. 
     
     
       10. The wireless charging receiver system of  claim 9 , wherein the two flat edges of the outer edge of the ferromagnetic shield are coplanar with corresponding outer edges of the first and second straight segments of the primary coil. 
     
     
       11. A portable electronic device, comprising:
 a housing comprising a top portion and a bottom portion configured to mate with the top portion to form an internal cavity; and 
 a wireless charging receiver system configured to receive power from time-varying magnetic fields propagating through the bottom portion of the housing, the wireless charging receiver system comprising:
 a primary coil formed of a plurality of turns of stranded wire wound about a primary axis and configured to receive wireless power from time-varying magnetic fields generated at a first frequency and in a first direction; 
 a ferromagnetic shield disposed over at least two adjacent surfaces of the primary coil and over a portion of the entire circumference of the at least two adjacent surfaces such that an annular segment of the primary coil is uncovered by the ferromagnetic shield; and 
 a secondary coil formed of a plurality of turns of stranded wire wound about a secondary axis disposed along a circumference centered around the primary axis, the secondary coil covers overlapping portions of the ferromagnetic shield and the primary coil and is configured to receive wireless power from time-varying magnetic fields generated at a second frequency different from the first frequency and in a second direction different from the first direction. 
 
 
     
     
       12. The portable electronic device of  claim 11 , wherein the ferromagnetic shield extends from a first radial location to a second radial location different from the first radial location. 
     
     
       13. The portable electronic device of  claim 12 , wherein the secondary coil extends from a third radial location to a fourth radial location different from the third radial location. 
     
     
       14. The portable electronic device of  claim 11 , wherein the at least two adjacent surfaces of the primary coil comprise an inner surface of the primary coil and a top surface of the primary coil. 
     
     
       15. The portable electronic device of  claim 11 , wherein the secondary coil and the annular segment of the primary coil that is uncovered by the ferromagnetic shield are positioned in opposite halves of the wireless charging receiver system. 
     
     
       16. A wireless charging system, comprising:
 a wireless charging transmitter comprising:
 a housing having a charging surface; and 
 at least one transmitter coil formed of a plurality of turns of stranded wire disposed within the housing and below the charging surface, the at least one transmitter coil configured to generate time-varying magnetic fields through and above the charging surface; and 
 a wireless charging receiver comprising: 
 a primary coil formed of a plurality of turns of stranded wire wound about a primary axis and configured to receive wireless power from time-varying magnetic fields generated at a first frequency and in a first direction; 
 a ferromagnetic shield disposed over at least two adjacent surfaces of the primary coil and over a portion of the entire circumference of the at least two adjacent surfaces such that an annular segment of the primary coil is uncovered by the ferromagnetic shield; and 
 a secondary coil formed of a plurality of turns of stranded wire wound about a secondary axis disposed along a circumference centered around the primary axis, the secondary coil covers overlapping portions of the ferromagnetic shield and the primary coil and is configured to receive wireless power from time-varying magnetic fields generated at a second frequency different from the first frequency and in a second direction different from the first direction. 
 
 
     
     
       17. The wireless charging system of  claim 16 , wherein the ferromagnetic shield extends from a first radial location to a second radial location different from the first radial location. 
     
     
       18. The wireless charging system of  claim 17 , wherein the secondary coil extends from a third radial location to a fourth radial location different from the third radial location. 
     
     
       19. The wireless charging system of  claim 16 , wherein the at least two adjacent surfaces of the primary coil comprise an inner surface of the primary coil and a top surface of the primary coil. 
     
     
       20. The wireless charging system of  claim 16 , wherein the secondary coil and the annular segment of the primary coil that is uncovered by the ferromagnetic shield are positioned in opposite halves of the wireless charging receiver.